Managing Your HVAC System

3 Options For Diagnosing Your Cold Furnace

A furnace that refuses to put out heat isn't doing you much good, and it might leave you out in the cold on a frigid winter day. While calling a technician is the best way to resolve severe issues, you may want to narrow down the source of trouble first. If you're feeling up to a bit of exploration around your HVAC equipment, you may be able to rule out a few common causes on your own.

Note that your furnace can pose some hazards, so don't attempt basic diagnostics unless you have experience. You should also know how to cut power to your furnace before you start working. Once you've covered the basics, you can try these three relatively straightforward diagnostic options.

1. The Basics — Switches, Filters, and Breakers

If your furnace isn't turning on, a good rule of thumb is to start with the basics first. Taking this approach can help you avoid a costly technician visit when your furnace is working fine. Begin by checking the power switch near your furnace since it's easy to switch it off accidentally. You'll also want to investigate your breaker box and reset the breaker, if necessary.

A dirty filter can also cause your furnace to shut off or not turn on at all. Remove your filter and check its condition, replacing it if it appears dirty or clogged. If you haven't changed your filter in a few months, it might be a good idea to do so as a precaution. Once you have a new filter in place, you can try turning your furnace back on to see if the problem resolves itself.

2. High-Tech Detective Work — Error Codes

You've checked the essentials, and your furnace still won't turn on, so now what? Your next step is to look for error codes. These codes will vary between manufacturers, but you should be able to find an LED light on your control board. If it's flashing, you can use your owner's manual to decode the blinking error message. Some manufacturers may also use an LCD that displays a short, 2-digit error code.

However, remember that error codes are only a starting point. You'll still need to confirm the problem reported by your furnace, so it's generally not a good idea to blindly replace parts based on codes alone. Instead, this information can be helpful to pass along to your technician when scheduling a repair visit.

3. Order of Operations — Startup-Sequence Diagnosis

Finally, you can consider the startup sequence for a typical gas furnace. By going down the list of startup steps, you can determine where your furnace is having an issue. This process may allow you to narrow the problem down to your thermostat, draft inducer, or one of your furnace's several safety switches. Even if you don't know the ultimate cause, this process can provide you with a good starting point.

While these steps can provide you with some helpful information, it's always best to call in a professional for a complete diagnosis and repair. 

For more information on furnace repairs, contact a company near you.